The ECB's massive bond-buying plan should help boost the euro zone economy but will not be enough, International Monetary Fund chief Christine Lagarde said today.
Ms Lagarde urged euro zone governments to carry out structural reforms.
"It should help but it will not be enough to revive the European economy and boost growth alone," Lagarde said of the European Central Bank's announcement that it would pump hundreds of billions of new money into the euro zone.
"We need deep structural reforms that will help competitiveness," she stated.
"We'll see if it works," Lagarde told France 2 television when asked about the ECB plan. "Confidence is the key".
"There is a serious risk, against which the ECB is acting, of very weak inflation or even deflation," she added.
Meanwhile, Bank of England Governor Mark Carney today welcomed the ECB's decision to launch the programme, saying it would help maintain prosperity in Europe.
"I welcome steps that the ECB took yesterday to preserve medium-term prosperity in Europe," he told business and political leaders meeting in Davos.
"It doesn't deliver prosperity, but it creates the conditions for it," he said.
Carney also underlined the importance of preventing a spiral of falling prices. "What's absolutely crucial is that we have inflation in the right spot," he stated.